With Congress eager to leave town for five weeks, the Senate engaged in some brinksmanship Tuesday by passing legislation that patches the impending shortfall in the Highway Trust Fund (HTF) and continues transportation spending only through Dec. 19. The House-passed version (H.R. 5021) would continue highway funding and spending through May 31, 2015.

It’s now up to Republican leaders in the House to decide whether to accept the Senate version or to stand firm in hopes of forcing the Senate to reconsider before the August break. Negotiators likely are working on a compromise behind the scenes, and it may be a couple of days before either the House or Senate acts again on the legislation. So the Dec. 19 expiration is far from a sure bet at this stage, especially given that the White House has signaled that it would accept the House version.

According to the Dept. of Transportation’s latest projections, without further action the HTF could run out of money before Congress returns from its August break, although DOT has adopted some stopgap plans in case a fix isn’t forthcoming. Meanwhile, authority to spend money from the trust fund is scheduled to expire Sept. 30.

The Senate’s objective in shortening the term for the highway extension is to force Congress to act again this year with the hope of striking a deal on a longer-term measure during a lame-duck session following the November election.

Final passage of the Senate version of H.R. 5021 by a 79-to-18 vote came Tuesday evening after a series of four back-to-back votes on amendments to the House version. First, the Senate voted 71 to 26 to approve the version approved by the Senate Finance Committee – a measure that, like the House bill, would extend highway funding through May 2015 but with a different mix of funding mechanisms.

Then just minutes later, the Senate voted 66 to 31 to undo what it had just voted to do when it approved an amendment to reduce the funding and shorten the end date for the highway program extension to Dec. 19.

Two other amendments backed only by a majority of Republicans failed. One would have transferred responsibility for highway funding and development except for the Interstate highway system to the states. The other would have eliminated environmental limitations on transportation infrastructure projects following federally recognized disasters.

The American Trucking Associations (ATA) praised the Senate action and called on the House to adopt the Senate-passed version.

“ATA believes quickly passing a long-term, well-funded highway bill is in our national interest and we believe that a short-term patch to keep the Highway Trust Fund solvent is the best way to achieve that,” said Bill Graves, ATA’s president and CEO. “Continuing to manage our nation’s infrastructure by crisis is no way to provide America’s motorists and truckers with the world-class infrastructure they need.”